In mechanical watches, for a long time devices have been proposed that avoid manual winding of the barrel spring owing to the movements of the wearer. CH Patent No. 142 511, published in 1930, is very representative of the solutions that were already proposed at that time using an oscillating weight, with simple or dual action, whose pinion drives a reducer kinematic chain which will rewind the spring.
Numerous improvements have been made to this principle as regards the shape, the nature or placing of the weights, and their point of pivoting.
It was also very quickly realised that the efficiency of an oscillating weight for automatic winding depends on the extent of activity of the wearer, but also and perhaps more importantly, on the initial impulse that it was given, for the balance movement to be able to be maintained thereafter by the ordinary movements of the wearer.
In order to create this initial impulse, without imposing excessive agitation of the wearer, various solutions have already been proposed.
CH Patent No. 317 534 discloses a device wherein a semi-circular pendular element pivots between two plates of the main oscillating weight in order to create the initial impulse. In CH Patent No. 149 136, the initial impulse is provided by a moving load (mercury, steel ball, etc. . . . ) arranged in a housing formed inside the main oscillating weight.
These constructions are relatively complicated and cumbersome, and have never, to the knowledge of the Applicant, been integrated into a timepiece movement released on the market.